Light emitting device

ABSTRACT

A light emitting device according to one aspect includes a resin package and a light emitting element. The resin package includes a molded resin part defining a part of a recessed portion, and a pair of leads. The leads are exposed from the molded resin part at a bottom surface of the recessed portion. Each of the leads includes a plating layer and exposed from the molded resin part at a lower surface of the resin package. A height of a first part of the plating layer exposed from the lower surface of the resin package and adjacent to an edge of a corresponding one of the leads is different from a height of a second part of the plating layer exposed from the lower surface of the resin package. The light emitting element is mounted on the bottom surface of the recessed portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 15/416,221, filed on Jan. 26, 2017, which is a continuationapplication of U.S. patent application Ser. No. 14/973,896, filed onDec. 18, 2015, now U.S. Pat. No. 9,590,158. This application claimspriority to Japanese Patent Application Nos. 2014-258845 and No.2015-244904 filed on Dec. 22, 2014 and Dec. 16, 2015, respectively. Theentire disclosures of U.S. patent application Ser. Nos. 15/416,221 and14/973,896, and Japanese Patent Application Nos. 2014-258845 and No.2015-244904 are hereby incorporated herein by reference.

BACKGROUND 1. Field of the Invention

The present disclosure relates to a light emitting device.

2. Description of the Related Art

Among light emitting diodes (LEDs) and other such light emitting devicesthat make use of a semiconductor light emitting element (hereinafterreferred to as a “light emitting element”), there are known devices thatmake use of a package made up of a resin and a lead. The main componentof the lead is a metal board made of copper or the like, and the surfaceof which is plated.

The leads used in light emitting devices are often plated with amaterial having high heat dissipation property, such as cupper, andanother material having high reflectivity, such as silver formedthereon. Plating layer with another material first as an underlayer is aknown way to make it easier to form the silver plating layer on theoutermost surface of the metal board. Example of the underlayer includenickel and the like (for example, JP2011-71471A and JP2008-192837A).

SUMMARY

A light emitting device according to one aspect includes a resin packageand a light emitting element. The resin package includes a molded resinpart defining a part of a recessed portion, and a pair of leads. Theleads are exposed from the molded resin part at a bottom surface of therecessed portion. Each of the leads includes a plating layer and exposedfrom the molded resin part at a lower surface of the resin package. Aheight of a first part of the plating layer exposed from the lowersurface of the resin package and adjacent to an edge of a correspondingone of the leads is different from a height of a second part of theplating layer exposed from the lower surface of the resin package. Thelight emitting element is mounted on the bottom surface of the recessedportion.

A light emitting device according to another aspect includes a resinpackage and a light emitting element. The resin package includes amolded resin part defining a part of a recessed portion, and a pair ofleads. The leads are exposed from the molded resin part at a bottomsurface of the recessed portion. Each of the leads includes a platinglayer. A lower surface of each of the leads has a first section and asecond section that are exposed from the molded resin part at a lowersurface of the resin package with the first section being substantiallyflush with the lower surface of the resin package and the second sectionbeing disposed closer toward an upper surface of a corresponding one ofthe leads than the first section with respect to a thickness directionof the corresponding one of the leads. The light emitting element ismounted on the bottom surface of the recessed portion.

According to the light emitting device of the present disclosure, it ispossible to provide a light emitting device in which a silver-platedlead is used, with the light emitting device having improved heatdissipation.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a schematic cross sectional view illustrating a lightemitting device according to an embodiment;

FIG. 1B is a partial enlarged view of the leas of FIG. 1A;

FIG. 1C is a schematic perspective view of the light emitting device ofFIG. 1A;

FIG. 1D is an enlarged view of X in FIG. 1C;

FIG. 2 is a schematic cross sectional view illustrating part of the leadaccording to an embodiment;

FIG. 3A is a schematic cross sectional view illustrating a lightemitting device according to an embodiment of;

FIG. 3B is a partial enlarged view of FIG. 3A;

FIG. 3C is a schematic bottom view illustrating the light emittingdevice of FIG. 3A; and

FIG. 4 is a schematic cross sectional view illustrating part of the leadaccording to another embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENT

Embodiments for implementing the light emitting device of the presentinvention will be described below with reference to the accompanyingdrawings. In the following embodiment of the light emitting device thatembody the technological concept of the present invention are justexamples, and so forth of the constituent parts discussed in theembodiment are not intended to limit the scope of the present invention,and are merely examples given for the sake of illustration.

In the specification, the constituent of the present invention is notintended to limit the constituent parts discussed in the embodiments. Inthe following embodiment, however, that embody the technological conceptof the present invention are just examples, and unless otherwisespecified, the dimensions, materials, shapes, relative layout. The sizesand the arrangement relationships of the members in each of drawings areoccasionally shown exaggerated for ease of explanation. Further, in thedescription below, the same designations or the same reference numeralsmay, in principle, denote the same or like members and duplicativedescriptions will be appropriately omitted.

In this Specification, in reference to the lead or the metal board, thesurface that is on the side where the light emitting element is mountedwhen used as a light emitting device shall be called the “uppersurface”, the surface opposite the upper surface shall be called the“lower surface”, and the surfaces between the upper surface and lowersurface shall be called the “lateral side surfaces”.

The light emitting device according to this embodiment is a lightemitting device including a package equipped with a lead having an uppersurface and a lower surface, and a molded resin that holds the lead sothat the lower surface of the lead is exposed to the outside; a lightemitting element mounted on an mounting portion on the upper surface ofthe lead; and a sealing member that seals the light emitting element.The lead has a metal board whose main component is copper, and platinglayer provided to the surface of the metal board. The plating layer onthe lower surface of the lead has a first plating layer that containssilver and nickel and is formed on the edge of the metal board, and asecond plating layer that does not contain nickel and is formed belowthe mounting portion of the light emitting element.

The lower surface of the light emitting device is such that the lowersurface of the lead is exposed to the outside, and is mounted to asecondary substrate with solder or another such adhesive agent. Becausethere is plating layer as second plating layer that has no nickel, whichhas low thermal conductivity, is provided directly under (or beneath)the light emitting element, heat produced by the light emitting elementcan be easily dissipated to the outside.

Nickel is suitable as a material that helps prevent the metal (andparticularly copper) that makes up the metal board, which is the basemember of the lead, from diffusing into the interior of the platinglayer. Accordingly, the diffusion of copper into silver can be moderatedby forming plating layer (first plating layer) that contains silver andnickel as the plating layer formed on the edge of the lower surface ofthe lead, and more precisely, by using plating layer (Cu/Ni/Au) in whichnickel is interposed between copper and silver. Copper is susceptible tooxidation. The solder that is used for mounting to a secondary substratedoes not adhere well to oxidized copper, so a region of goodsolderability (joinability) can be formed by forming first platinglayer, in which the diffusion of copper has been moderated, on the lowersurface of the lead.

As discussed above, the plating layer on the lower surface of the leadincludes (preferably consists of) two kinds of plating layer, namely,plating layer with good heat dissipation (i.e., second plating layer),and plating layer with good adhesion to solder (i.e., first platinglayer), and as a result, a light emitting device with good heatdissipation can be obtained with little decrease in adhesion to thesecondary substrate.

Also, it is preferable to provide nickel on the side where the lightemitting element is mounted, that is, the upper surface side of the lead(metal board). This makes it less likely that the metal constituting themetal board (and particularly copper) will diffuse into the interior ofthe plating layer, moderates the deterioration of the silver formed overthis, and thereby reduces a decrease in reflectivity, a decrease ingloss, and so forth. However, because the thermal conductivity of nickelwill be lower than that of the metal board, this can lead to a drop inheat dissipation. Accordingly, the plating layer formed in the regionwhere light from the light emitting element is not applied, that is, theplating layer formed on the lower surface of the metal board, can beplating layer that does not contain nickel (i.e., second plating layer),and this helps avoid a decrease in heat dissipation.

Package

The package comprises a lead and a molded resin that holds the lead. Thepackage can have a flat shape, or it can have a shape in which a recessthat allows the light emitting element to be mounted is provided, etc.With a flat package, the upper surface of the lead is exposed on theupper surface of the package. With a package having a recess, the uppersurface of the lead is exposed on the bottom surface of the recess. Thebottom surface of a lead is exposed on the lower surface of the package.

Lead

The lead functions as the electrodes of the light emitting device, andhas at least two leads: a positive electrode lead and a negativeelectrode lead. The leads are flat metal members that have beenpatterned in a specific shape, and have a metal board that serves as thebase member, and plating layer formed on the surface of the metal board.The lead may have a portion which does not function as the electrodes ofthe light emitting device such as a heat dissipation portion.

Metal Board

The metal board is patterned in the desired shape by etching, pressing,punching, blasting, or another such working method. The metal board isworked so as to have a plurality of patterns so that a plurality oflight emitting devices can be obtained with a leadframe. Each patternincludes parts that function as heat dissipation portions or the like,or a pair of positive and negative leads that function as electrodeterminals when used as a light emitting device, and furthermore thereare linking portions for linking the various patterns, other parts, etc.There may also be cut-off portions, recesses, holes, or the like. Thisworking can be performed before or after the plating, but is preferablyperformed before plating.

Examples of the material of the metal board include copper, aluminum,silver, gold, zinc, chrome, tungsten, cobalt, nobelium, rhodium,ruthenium, and other such metals and alloys of these. A single layer maybe used, or a multi-layer structure, such as a clad material can beused. It is preferable to include copper as the main component, forexample, at 90% by weight or more. Also, silicon, phosphorus, and othersuch non-metals may be contained as trace elements.

The thickness of the metal board is preferably between about 100 and1000 μm, for example, and more preferably between about 200 and 500 μm.The entire metal board may have this thickness, or part of it may bethinner. In particular, the portion that becomes the edge in patterningmay have a shape that includes a depressed portion on the lower surfaceside of the lateral side surface, or in other words, a shape thatincludes a protruding portion on the upper surface side of the lateralside surface. The thickness of this protruding portion can be aboutone-half to one-fifth the thickness of the other portions (such asdirectly below the light emitting element). Using such shape improvesadhesion between the lead and the molded resin when a package is formed.Also, in the case where the lead is disposed so as to be exposed on thelower surface of the package, this protruding portion or depressedportion provided to the edge of the lead will provide an anchoringeffect that prevents the lead from coming loose from the molded resin.

Plating Layer

Plating layer is provided to the surface of the metal board. The lowersurface of the metal board is plated with two different compositions: afirst plating layer that contains silver and nickel, and a secondplating layer that does not contain nickel. The second plating layer isprovided beneath (directly under) the mounting portion of the lightemitting element. The second plating layer may be provided to at leastpart of the area beneath the mounting portion of the light emittingelement, and preferably is provided beneath the entire region of themounting portion of the light emitting element. The first plating layeris provided to the edge of the lower surface of the metal board. In thiscase, the first plating layer may be provided to at least part of theedge of the lower surface of the metal board, and may further beprovided to the edge that extends about one-half to one-fifth the wayaround, and may be provided all the way around. The lead where no lightemitting element is mounted does not necessarily have to be providedwith the second plating layer on its lower surface (i.e., the lowersurface of the metal board). For example, the first plating layer may beprovided over the entire surface, or a third plating layer that isdifferent from the first and second plating layer may be provided, or noplating layer may be provided so that the metal board is left exposed.

A degreasing process is preferably provided to remove organic substancesfrom the lead surface, as a pretreatment prior to forming the first andsecond plating. Furthermore, lead surface activation is preferablyperformed by acid treatment or the like following the degreasing step.

In this Specification, metal elements of the “nickel” and “silver” thatmake up the plating layer do not refer to plating layer composed solelyof these metals, and instead, as referred to the fact, these are themain components, and refer to a material that contains at least 70 wt %nickel or silver. Specifically, this terminology is used merely for thesake of convenience, and encompasses situations in which the platinglayer contains unavoidable impurities, materials of less than 30 wt %,etc.

First Plating Layer

The first plating layer, which includes nickel and silver formed on thenickel, is provided to part of the lower surface of the metal board.More precisely, the lower surface of the metal board, at least part ofthe area beneath the mounting portion of the light emitting element isprovided with the second plating layer, and the first plating layer isprovided to a different region from that of the second plating layer.Specifically, the first plating layer is provided to the lower surfaceof the metal board, except for at least part of the region where thelight emitting element is mounted. For example, the first plating layercan be provided to the edge of the lower surface of the metal board soas to be continuous from the lateral side surfaces.

As discussed above, nickel not only reduces diffusion of copper andother such elements of the metal board into the plating layer (silver asthe element), but also improves the adhesion of the respective platinglayers. Accordingly, by providing the first plating layer, whichcontains nickel and is formed with good silver adhesion, to part of thelower surface of the metal board (and particularly to the edge), thesilver plating layer can be positioned on the outermost surface in astate of moderated diffusion of copper, and good solder adhesion can beachieved.

In addition to nickel and silver, other materials can also be stacked inthe first plating layer structure. Examples of such materials includegold, copper, platinum, palladium, aluminum, tungsten, molybdenum,ruthenium, and rhodium. Examples of the multi-layer structure includeNi/Ag, Ni/Pd/Ag, Ni/Pd/Au/Ag, Ni/Pt/Ag, Ni/Au/Ag and Cu/Ni/Pd. Amongthem, the laminated structure of Ni/Pd/Au/Ag and Ni/Au/Ag areparticularly preferable.

Also, the first plating layer may be provided to the upper surface andlateral side surfaces of the metal board. For instance, the firstplating layer is formed continuously on the upper surface and thelateral side surfaces of the metal board by covering part of the lowersurface of the patterned metal board (beneath the region where the lightemitting element is mounted) with a mask (such as a resist mask or amask made of protective tape), dipping it in a plating bath to formnickel plating layer, and then removing the mask and forming silverplating layer. When the silver plating layer is formed in this way, itis formed integrally as plating layer which has both the first platinglayer and the second plating layer. A configuration such as this can beachieved by applying a partial nickel plating layer as an underlayer.The first plating layer and the second plating layer may thus share partof the plating layer, or they may have completely differentconfigurations.

The first plating layer formed continuously with the lower surface, thelateral side surfaces and the upper surface of the metal board allowscorrosion of the base metal in the first plating layer to be moderated,compared with the first plating layer formed only on the lower surfaceof the metal board.

In the case of including the protruding portion on the upper surfaceside of the lateral side surface of the metal board, the first platinglayer is preferably formed on the lateral side surfaces and a lowersurface of the protruding portion. Further, the first plating layer ispreferably formed on the lateral side surfaces of the depressed portionof the metal board which is located under the protruding portion on thelateral side surface of the metal board.

The lead has an exposed portion on the lateral side surface of the lightemitting device. In the case that the each light emitting device isformed by separating an array of the light emitting devices, the lateralside surfaces are formed from the separation surfaces. That is, thelateral side surfaces of the light emitting device are formed from aseparation face of the molded resin and a separation face of the lead.The plating layer is formed before the molded resin is formed, in otherwords, the plating layer is formed on each lead in the state of the leadframe. Therefore, the lateral side surfaces of the lead which are formedby separating of the array of the light emitting devices, in otherwords, the side surfaces which are exposed on the lateral side surfaceof the light emitting device, are not covered by the plating layer. Theplating layer is formed so as to surround the metal board at the lateralside surface of the metal board. The exposed plating layer here is thefirst plating layer, and contains nickel. Since nickel is harder thanthe metal board of copper, the separation portion of the first platinglayer containing nickel allows burr of copper to be reduced.

Also, in the plating step, when a masking belt is used rather than aresist mask or a mask made of protective tape, the belt that comes intocontact with the edge of the patterned portion of the lower surface ofthe metal board does not fit so snugly that there is no gap, so thefirst plating layer is also formed between the metal board and the belt.Consequently, the nickel plating layer is formed so that the thicknessis different on the lower surface of the metal board. In this case, theplating layer may be formed so that it becomes thinner as it is fartheraway from the end of the lower surface of the metal board.

Second Plating Layer

The portion of the lower surface of the metal board that is beneath theregion where the light emitting element is mounted has second platinglayer that does not contain nickel. The no nickel here is defined tomean that no nickel is intentionally used or added when forming thesecond plating layer; however, there is a room for a possible presenceof impurities that might contain nickel. The second plating layer may beprovided beneath at least a part of the region where the light emittingelement is mounted, and preferably is provided over at least half theregion where the light emitting element is mounted, and more preferablyis provided beneath the entire mounting region. Also, the first platinglayer is provided to part of the lower surface of the metal board, andthe second plating layer is preferably provided so as to come intocontact with this first plating layer. That is, the second plating layerdoes not contain nickel.

The second plating layer can be formed simultaneously with part of theplating layer that makes up the first plating layer. For example, informing nickel plating layer on the upper surface of the metal board, inthe case where a location corresponding to beneath the region where thelight emitting element is mounted is masked and plated, and the entiresurface of the metal board is plated with something other than nickelwithout any masking, plating layer of part of the first plating layer(plating layer other than nickel) and the second plating layer can beformed in the same step. This method realize a structure in which theplating layer other than nickel is provided continuously from the uppersurface to the lower surface of the metal board.

Examples of the material of the second plating layer include silver,gold, copper, cobalt, zinc, rhodium, chromium, aluminum, tungsten,molybdenum, ruthenium, and rhodium. These can be used singly, or, justas with the first plating layer, a multi-layer structure can be used inwhich the second plating layer also includes an underlayer or the like.Au/Ag is an example of a multi-layer structure.

Also, plating may be performed for forming third plating layer after themolded resin has been formed. A Plating layer (e.g., solder platinglayer) that contains lead, tin, silver, copper, bismuth, or the like,for example, may be formed as this third plating layer. In the casewhere plating layer is thus formed after molding, the lower surface ofthe lead will have a shape that protrudes more than the lower surface ofthe molded resin, and stable joint strength can be maintained duringsecondary mounting. Also, since the plating layer is formed aftermolding, it can be formed on only where needed, which reduces the amountof material used.

The total thicknesses of the first plating layer and second platinglayer is preferably between about 1 and 10 μm, and more preferablybetween 1.5 and 6 μm, respectively. The thickness of each layer can besuitably selected as dictated by the intended application. For instance,the thickness of the nickel layer may be about between 0.1 and 5 μm,preferably between about 0.5 and 5 μm, palladium between about 0.005 and0.05 μm, gold between about 0.001 and 0.5 μm, and silver between about 1and 5 μm.

Molded Resin

The molded resin functions as a holding member that integrally holds atleast two leads in producing a light emitting device, and also functionsas a member that controls optical characteristics, such as opticalreflectivity and light blocking. The molded resin is provided between apair of leads, and also functions as an insulating member that keeps thepositive and negative leads from coming into contact with each other.

The reads are preferably disposed so that their lower surfaces areexposed from the lower surface of the package. The upper surface of alead includes an element mounting region where a light emitting elementis mounted, and, when a wire is used, a wire connection region where awire is connected. These are disposed so as to be exposed from themolded resin.

Examples of the resin material used for the molded resin includethermosetting resins, thermoplastic resins, and other such resins.Specific Examples of the thermosetting resin include an epoxy resincomposition; a silicone resin composition; a modified epoxy resincomposition, a modified silicone resin composition, a silicone modifiedepoxy resin; an epoxy modified silicone resin; a polyimide resincomposition, a modified polyimide resin composition, an unsaturatedpolyester resin composition, diallyl phthalate, and specific examples ofthe thermoplastic resin include a polyamide, a polyphthalamide (PPA), apolycarbonate resin; a polyphenylene sulfide (PPS); a liquid crystalpolymer (LCP); an ABS resin (an acrylonitrile-butadiene-styrene resin);a phenolic resin; an acrylic resin; and a PBT resin (polybutyleneterephthalate resin). These may be used singly, or by a combination oftwo or more types. A thermosetting resin is particularly preferable. Itis especially preferable for the molded resin to be one whosereflectivity with respect to the light from the light emitting elementis at least 60%, more preferably 70%, 80%, or 90% or more when used fora light emitting device.

The molded resin may also contain titanium oxide or another such lightreflecting material. Examples of the reflecting material includetitanium oxide, silicon oxide, zirconium oxide, potassium titanate,alumina, aluminum nitride, zinc oxide, boron nitride and mullite. Thisallows the light from the light emitting element to be reflectedefficiently. It may also contain carbon black or another suchblack-color material. The light reflecting material or black-colormaterial can be suitably adjusted according to the molding conditions,such as resin molding method, resin fluidity, or according to thereflectivity, mechanical strength, or other such characteristics. Forinstance, when titanium oxide is used, it is preferably contained in anamount of between 10 and 60 wt %, and more preferably between 15 and 50wt %, with respect to the total weight of the molded resin.

Light Emitting Element

The light emitting element is constituted by a semiconductor layerincluding a light emitting layer, stacked on an element substrate.Alternatively, it may be constituted by a semiconductor layer obtainedby removing the substrate after stacking a semiconductor layer thatincludes a light emitting layer on an element substrate.

There are no particular restrictions on the element substrate, but anexample is one that is normally used to grow a nitride semiconductorlayer. A light-transmissive substrate is particularly preferable. Theterm light-transmissive here refers to a property of being able totransmit at least about 60%, 65%, 70% or 80% of the light emitted fromthe light emitting element. Example thereof include sapphire, spinel,NGO, LiAlO₂, LiGaO₃ and GaN. An element substrate composed of an oxideis particularly preferable, an element substrate composed of a Wurtzitetype crystal is more preferable, and sapphire is still more preferable.

The semiconductor layer stacked on the element substrate preferably hasat least a light emitting structure. More specifically, thesemiconductor layer is configured, for example, such that a firstsemiconductor layer (i.e., n-type or p-type semiconductor layer), alight emitting layer, optionally via a buffer layer or other such layeror layers, and a second semiconductor layer (I.e., p-type or n-typesemiconductor layer) are stacked in that order on a substrate.

In this semiconductor layer, part of region is removed in the thicknessdirection from the second semiconductor layer side, that is, the layeris partially removed, the first semiconductor layer is exposed fromthere, and the light emitting layer and the second semiconductor layerare stacked in that order on the other region of the first semiconductorlayer besides this exposed region.

There are no particular restrictions on the first semiconductor layer,light emitting layer, and second semiconductor layer that make up thesemiconductor layer, but a nitride compound semiconductor such asIn_(X)Al_(Y)Ga_(1-X-Y)N (0≤X, 0≤Y, X+Y≤1) can be used to advantage, forexample. The nitride semiconductor layer may be a single-layerstructure, or it may be multi-layer structure having layers of differentcomposition, thickness, and so forth, a super-lattice structure, or thelike. It is particularly favorable for the light emitting layer to havea single quantum well or a multiple quantum well structure in whichthin-films with a quantum effect are stacked.

A pair of electrodes had by the light emitting element are disposed onthe same surface side of the semiconductor layer. These electrodes mayhave a single-layer structure or a multi-layer structure, so long asthey are ohmically connected so that the current-voltage characteristicsare linear or substantially linear. These electrodes can be formed inthe desired thickness, with any configuration and materials that areknown in this field. For example, the thickness is preferably between afew dozen microns about 300 μm.

In particular, in the case where the pair of electrodes of the lightemitting element are each electrically connected to leads via a joiningmember, it is preferable to dispose a reflective layer (e.g., a platinglayer or DBRs) as the layer of the electrodes closest to thesemiconductor layer side.

Also, the light emitting element may be a white light emitting elementin which a phosphor layer has been formed in advance, or a white lightemitting element in which a phosphor layer has been formed on the uppersurface, and lateral side surfaces of the light emitting element iscovered by a resin or by a metal or another such reflective layer.Furthermore, a light emitting element can be used in which the thicknessof the electrodes disposed on the mounting surface from the lightemitting element is increased, and a resin (i.e., white resin) or othersuch stress moderation layer is provided around the periphery thereof.

Joining Members

The pair of electrodes of the light emitting element are electricallyconnected to the leads via a wire or a joining member.

An insulating joining member or a conductive joining member can be used,for example, as the joining member. A resin is an example of aninsulating joining member, which can be a light transmissive resin, awhite resin, or the like. Examples of conductive joining members includeeutectic materials such as those based on alloys whose main componentsare gold and tin, alloys whose main components are gold and silicone,alloys whose main components are gold and germanium, and solder such asthose based on alloys whose main components are silver, copper and tin,those based on alloys whose main components are copper and tin, thosebased on alloys whose main components are bismuth and tin. Of these, aeutectic alloy of Au—Sn is preferable. Using an Au—Sn eutecticalloymoderates degradation caused by thermal compression bonding on theelectrodes of the light emitting element, and it can be joined moresecurely to the leads.

Sealing Members

The sealing members are used to protect the light emitting element, aprotective element, a wire, or other such electronic parts mounted inthe package against dust, moisture, external force, and the like. Thematerial of the sealing member is preferably transmissive enough totransmit the light from the light emitting element, and is lightresistant enough not to be readily degraded by the light. Specificexamples of materials include silicone resin compositions, modifiedsilicone resin compositions, epoxy resin compositions, modified epoxyresin compositions, acrylic resin compositions, and other suchinsulating resin compositions that are transmissive enough to transmitthe light from the light emitting element. It is also possible to use asilicone resin, an epoxy resin, a urea resin, a fluororesin, a hybridresin that includes one or more of these resins, or the like.Furthermore, the sealing member is not limited to being one of theseorganic substances, and can instead be glass, a silica sol, or anothersuch inorganic material. In addition to these materials, a colorant, alight diffusing agent, a light reflecting material, any of variousfillers, a wavelength conversion member (e.g., fluorescent member), orthe like can also be contained as desired. The sealing member may beused in an amount large enough to cover the above-mentioned electronicparts.

The shape of the outer surface of the sealing member can be variouslyselected according to the light distribution characteristics and soforth. Directional characteristics can be adjusted by giving the uppersurface a convex lens shape, a concave lens shape, a Fresnel lens shape,or the like, for example. Also, a lens member may be provided inaddition to the sealing member. Furthermore, in the case where aphosphor-containing molded article (such as a phosphor-containing flatmolded article, or a phosphor-containing dome-shaped molded article) isused, it is preferable to select a material with good adhesion to thephosphor-containing molded article as the sealing member. Besides aresin composition, glass or another such inorganic substance can be usedas the phosphor-containing molded article.

Examples of phosphors include oxide-based phosphor, sulfide-basedphosphor, and nitride-based phosphor. For instance, when a galliumnitride light emitting element that emits blue light is used as thelight emitting element, examples include LAG materials and YAG materialsthat absorb blue light and emit yellow to green light, SiAlON (β-SiAlON)materials that emit green light, SCASN materials, CASN materials,KSF-based phosphors (K₂SiF₆:Mn), and sulfide-based phosphors that emitred light, and other such phosphors, which can be used singly or incombination.

The light emitting device may further have a Zener diode, a bridgediode, or another such protective element.

Embodiment 1

FIG. 1A is a schematic cross sectional view of a light emitting device100 according to Embodiment 1, and FIG. 1B is a partial enlarged view ofthe lead 12, FIG. 1C is a schematic perspective view of the lightemitting device of FIG. 1A, and FIG. 1D is an enlarged view of X in FIG.1C. The light emitting device 100 includes a package 10 equipped with arecessed portion, a light emitting element 140 that is mounted on thebottom surface of the recessed portion of the package 10, and a sealingmember 120 that fills the recessed portion so as to cover the lightemitting element 140. The light emitting element 140 is electricallyconnected to leads 12 via wires 160. The package 10 includes two leads12 that become a pair of positive and negative electrodes, and a moldedresin 14 that holds the leads and has a bottom surface and lateral sidesurfaces. Parts of the upper surfaces of the leads 12 are exposed at thebottom surface of the recessed portion, and substantially all of thelower surfaces are exposed and disposed so as to become the lowersurface of the light emitting device 100. The leads 12 has exposedportions 12 a which are exposed on the lateral side surfaces of thelight emitting device as shown in FIG. 1C.

The each lead 12 includes a metal board 2 composed of copper as the basemember of the leads and plating layer 4 that is formed on the surface ofthe metal board 2. The lower surface of the metal board is provided withfirst plating layer 4A in which nickel layer 41 and silver layer 42 arestacked, and second plating layer 4B that does not include nickel. Thenickel layer 41 is provided in a substantially uniform thickness overthe lower surface of the metal board 2. This can be obtained byproviding a mask using protective tape over the lower surface of themetal board 2 and plating layer with nickel.

The second plating layer 4B is provided integrally with the silver layer42 in the first plating layer 4A. On the lower surface of the metalboard 2, the first plating layer 4A and the second plating layer 4B areformed so that their surfaces are flush. The first plating layer 4A, thesecond plating layer 4B, and the molded resin 14 are formed so that theywill be flush at the lower surface of the light emitting device.

Plating layer with the same constitution as the first plating layer 4Aprovided to the lower surface of the metal board 2 is provided over theentire upper surface of the metal board 2. The exposed portion 12 a,which is exposed on the lateral side surface of the light emittingdevice, is formed such that the first plating layer 4A and the secondplating layer 4B surround the surface of the metal board 2 as shown inFIG. 1D.

This configuration allows heat from the light emitting element to beeasily released to the outside. It also moderates a decrease injoinability of the leads with solder. Further, the plating layercontaining nickel at a portion in which the exposed lead is cut allowsburr of the metal board 2 to be suppressed.

Embodiment 2

FIG. 2 is a partial enlarged view of the leads 12. In Embodiment 2, thefirst plating layer 4A provided to the lower surface of the metal board2, the thickness of the nickel 41 is not uniform, and instead varies.More precisely, this differs from Embodiment 1 in that the thicknessdecreases as it is farther away from the end of the lower surface of themetal board 2. This is obtained by applying a masking belt so as to comeinto contact with the lower surface of the metal board 2 for platinglayer with nickel.

Embodiment 3

FIG. 3A is a schematic cross sectional view of a light emitting device200 according to Embodiment 3, and FIG. 3B is a partial enlarged view ofthe lead 12, and FIG. 3C is a schematic bottom view illustrating thelight emitting device 200. In Embodiment 3, the silver layer 42, whichis the second plating layer 4B provided to the lower surface of themetal board 2, is formed in the same thickness as the silver layer 42 inthe first plating layer 4A. The first plating layer 4A has the nickellayer 41 formed as an underlayer of the silver layer 42, and the silverlayer 42 is formed over it, and the silver layer 42 of the secondplating layer 4B is formed at the same time as the silver layer 42 inthe first plating layer 4A. This method results in the surface of thefirst plating layer 4A and the surface of the second plating layer 4Bbeing provided at different heights on the lower surface of the metalboard 2. Specifically, the first plating layer 4A sticks out beyond thesecond plating layer 4B. As shown in FIG. 3C, on the lead 12 which isexposed at the lower surface of the light emitting device 200, the firstplating layer 4A is formed at the portion in contact with the moldedresin (i.e., outer periphery), and the second plating layer 4B is formedat the portion which is surrounded by the first plating layer 4A. Thethickness of the first plating layer 4A is about between 1 and 100 μm,preferably about 5 to 75 μm, and more preferably about between 10 and 50μm or about between 20 and 50 μm on the lead 12 which is exposed at thelower surface of the light emitting device 200. The width of the firstplating layer 4A may be one of variable options such as partially-wideor partially-narrow width as well as a linear shape as shown in FIG. 3C.In this case, an average width may be within the above ranges.

Thus providing plating layer of different heights on the lower surfacesof the leads 12 affords better joinability with solder. Specifically,the first plating layer 4A sticks out beyond the second plating layer4B, and the first plating layer 4A is provided so as to be substantiallyflush with the molded resin. The surface of the second plating layer 4Bis formed as a surface that is lower than this. When this light emittingdevice 200 is mounted on a secondary substrate, there is more solderingsurface area between the second plating layer 4B and the secondarysubstrate. This improves joinability between the light emitting deviceand the secondary substrate.

Embodiment 4

FIG. 4 is an enlarged view of the lead 12. In Embodiment 4, thethickness of the nickel layer 41, which is the first plating layer 4Aprovided to the lower surface of the metal board 2, varies, and is notuniform. More precisely, this is the same as Embodiment 2 in that thethickness decreases as it is farther away from the end of the lowersurface of the metal board 2. Further, the silver layer 42, which is thesecond plating layer 4B provided to the lower surface of the metal board2, is formed with the same thickness as that of the silver layer 42 inthe first plating layer 4A. The first plating layer 4A has the nickellayer 41 formed as an underlayer of the silver layer 42, and the silverlayer 42 is formed over it. The silver layer 42 of the second platinglayer 4B is formed at the same time as the silver layer 42 of the firstplating layer 4A. This results in the surface of the first plating layer4A and the surface of the second plating layer 4B being provided atdifferent heights on the lower surface of the metal board 2.Specifically, the first plating layer 4A extends beyond the secondplating layer 4B.

INDUSTRIAL APPLICABILITY

The light source device of the present invention can be used in avariety of light sources, such as a lighting-use light source, variouskinds of indicator-use light source, a light source installed in/on avehicle, a display-use light source, a light source for a liquid crystalbacklight, sensor-use light source, and signaling devices. Also, it isapplicable to all the light-emitting device using leads such as aside-view type light emitting device.

What is claimed is:
 1. A light emitting device comprising: a resinpackage including a molded resin part defining a part of a recessedportion, and a pair of leads exposed from the molded resin part at abottom surface of the recessed portion, each of the leads including aplating layer and exposed from the molded resin part at a lower surfaceof the resin package, a height of a first part of the plating layerexposed from the lower surface of the resin package and adjacent to anedge of a corresponding one of the leads being different from a heightof a second part of the plating layer exposed from the lower surface ofthe resin package; and a light emitting element mounted on the bottomsurface of the recessed portion, wherein the plating layer includes afirst plating portion corresponding to the first part and a secondplating portion corresponding to the second part, the first platingportion includes silver and nickel, and the second plating portion doesnot include nickel.
 2. The light emitting device according to claim 1,wherein the first plating portion includes palladium plating layerbetween nickel plating layer and silver plating layer.
 3. The lightemitting device according to claim 2, wherein the second plating portionincludes silver.
 4. The light emitting device according to claim 2,wherein the second plating portion is arranged under an entire areacorresponding to a mounting portion of the light emitting element.
 5. Alight emitting device comprising: a resin package including a moldedresin part defining a part of a recessed portion, and a pair of leadsexposed from the molded resin part at a bottom surface of the recessedportion, each of the leads including a plating layer, a lower surface ofeach of the leads has a first section and a second section that areexposed from the molded resin part at a lower surface of the resinpackage with the first section being substantially flush with the lowersurface of the resin package and the second section being disposedcloser toward an upper surface of a corresponding one of the leads thanthe first section with respect to a thickness direction of thecorresponding one of the leads; and a light emitting element mounted onthe bottom surface of the recessed portion, wherein the plating layerincludes a first plating portion corresponding to the first section anda second plating portion corresponding to the second section, the firstplating portion includes silver and nickel, and the second platingportion does not include nickel.
 6. The light emitting device accordingto claim 5, wherein the first plating portion includes palladium platinglayer between nickel plating layer and silver plating layer.
 7. Thelight emitting device according to claim 5, wherein the second platingportion includes silver.
 8. The light emitting device according to claim5, wherein the second plating portion is arranged under an entire areacorresponding to a mounting portion of the light emitting element.